System for transporting objects to ocean structures

ABSTRACT

The invention provides a system for transporting object from a sea level position to an elevated position on a structure, wherein the sea level position is movable in relation to the elevated position. The system comprises an elongated guide device configured to be arranged to the structure in one end and to extend below the sea level with a second end, an attachment device configured to be arranged on said object and for attaching said object to the elongated guide device, wherein the attachment device is configured to allow a relative movement between the attachment device and the elongated guide device along a first direction parallel to the extension direction of the guide device and a lifting device configured to transport the object from the sea level position to the elevated position. The system is characterized in that a weight is arranged to the second end of the guide device below the sea level for stabilizing the guide device, wherein the second end is a free end and the weight is a free weight.

TECHNICAL FIELD

The present invention relates generally to system for transportingobjects to ocean structures.

BACKGROUND ART

Due to the incidence of accidents there are strict limitations regardingacceptable sea conditions when boarding or transporting objects to anocean structure such as for example an offshore oil or wind energyplatform. This limits the time window for maintenance and repair.

These are well-known problems and dangers within the industry, both whentransferring personnel, equipment and supplies to or from an oceanstructure. The same problem also arises when boarding a larger ship froma smaller boat.

To overcome these limitations boats are getting bigger and moresophisticated and the costs of equipment, personnel and fuel, areincreasing. The use of bigger boats have created new problems that canoccur when the boats accidentally collides into the platform/foundationstructure. If the platform/foundation structure and/or its corrosionprotection are damaged the consequences are severe.

Known boarding solutions are for example hanging transport baskets, wavecompensated gangways or cranes mounted on the boat transporting thepersonnel or equipment to the ocean structure.

It is also known to use boat lifts for use with ocean structuresincluding one or more mount components for attaching to side regions ofa boat. One or more mechanisms are coupling between the one or moremount components and the structure for operatively lifting up or downthe mount components relative to the structure. Such boat lift is knownfrom GB2479742 A.

A drawback with this systems is that the mechanisms, in the form ofupright members, are welded or otherwise affixed to the ocean structureby a plurality of connection points between the upright members and thestructure forming a rigid connection. A further drawback with suchsystem is that it comprises many components which makes it expensiveboth to manufacture, as well as install and/or replace on the oceanstructure.

SUMMARY OF INVENTION

An object of the present invention is to provide a system fortransporting objects to ocean structures which prevents personalinjuries and reduces the risk of damage to the boat/equipmenttransported to the structure or the structure itself.

A further object of the present invention is to provide a system fortransporting objects to ocean structures which is stable yet lesssusceptible to bending forces. The bending forces may cause damage tothe structure due to wear as a result of prolonged use, which in turnincreases the risk for operators or crew members.

A further object of the present invention is to provide a system fortransporting objects to offshore structures which are cost effective tomanufacture and install as well as replace.

According to one embodiment the invention provide a system fortransporting object from a sea level position to an elevated position ona structure, wherein the sea level position is movable in relation tothe elevated position. The system comprises;

-   -   an elongated guide device configured to be arranged to the        structure in one end and to extend below the sea level with a        second end,    -   an attachment device configured to be arranged on said object        and for attaching said object to the elongated guide device,        wherein the attachment device is configured to allow a relative        movement between the attachment device and the elongated guide        device along a first direction parallel to the extension        direction of the guide device, and to restrict movement along a        direction perpendicular to the first direction,    -   a lifting device configured to transport the object from the sea        level position to the elevated position,    -   The system is characterized in that a weight is arranged to the        second end of the guide device below the sea level for        stabilizing the guide device, wherein the second end is a free        end and the weight is a free weight.

The mass of the weight, the position of the weight and second end of theguide device sufficiently submerged below the sea level provides astable guide device adapted to be used for lifting heavy objects, at thesame time as it does not have to take up as high bending forces. Theattachment device allow a movement along one first direction andrestrict movement in a direction essentially perpendicular to the firstdirection. However, a play between attachment device and guide devicemay be present, allowing a limited movement in the direction essentiallyperpendicular to the first direction. Further, with a system constructedaccording to this embodiment, where the guide device has a free end witha weight for stabilizing the device, the guide device is able to pivotaround its attachment point to the structure and hence move slightlyrelative the structure. Thus, the guide device withstands less bendingforces on the respective parts than the previously known transport andboarding structures with a fixed guide member. Thus, such a system isnot as susceptible to wear, will have a longer life span and requireless service than the previous known solutions. Further, with a freeweight attached in one end of a guide device it is possible to move thetransport system away from the structure and to lift the objects at acertain distance from the structure, thus minimizing the risk ofcollision between the structure and object to be lifted during thevertical transportation. Further, the system is cheap to manufacturesince it comprises few parts, a majority of which are standard parts, aswell as being cheap to install as well as replace when necessary.

According to one embodiment the attachment device is configured forguiding the object from the sea level position to the elevated positionalong the elongated guide device when transported by the lifting device.

To use a separate lifting device to transport the object and only usethe attachment devices for guiding the object during the verticalmovement is a more reliable solution than previous known art. Further,it is possible to use lifting devices already present at the structureand thus to create a more cost efficient solution.

According to one embodiment the weight is arranged to the second end ofthe guide device at a position at least 5 m below sea level, preferablyat least 10 m below sea level, whereby the guide device is unaffected bymotions of the sea.

When arranging the weight a certain distance below sea level, thetransporting procedure is simplified since the guide device is keptstraight and stretched and stay unaffected of rough seas. The distancebelow sea level depend on the conditions present at the site where thestructure is located. The weight shall be arranged at a depth unaffectedby waves and sea current but shall hang free and not be attached to orrest on the bottom of the sea.

According to one embodiment the guide device comprises two parallelarranged guide wires having a distance from each other. Said guide wiresare in one embodiment made of steel.

Using two parallel arranged guide wires enables two attachment points tothe object to be transported. Thus, it enables hoisting of the objectwithout the object rotating and swinging. It is also easier to keep theobject horizontal during lifting.

According to one embodiment the distance between the guide wires is keptconstant by a beam extending between the guide wires or wherein theweight is made in one piece and extend between the guide wires.

A constant distance between the guide wires simplifies the attachmentprocedure when the object is docked to the guide device.

According to one embodiment, the attachment device comprises a first anda second attachment device part arranged to grip the respective guidewires.

When separating the attachment device in two attachment device parts itis possible to arrange the different parts on suitable positions on theobject to be transported. I.e. the attachment device parts may forexample be placed on opposite sides of a stern or stem if the object isa boat or vessel. If more than one object is to be attached to the guidedevice at the same time, for example a boat and a container where onlythe container is to be lifted, it is preferred that the respectiveattachment device parts are arranged at the respective object so that itis possible to attach the objects on different horizontal levels.

According to one embodiment, the weight comprises two separate blocksconnected by a beam. According to one embodiment, the weight has a massof 3-10 tons.

A weight having this specific mass is complicated to transport out tothe structure at sea. It is therefore an advantage if the weight can bemade or assembled at the structure. A weight comprising several parts iseasier to handle and transport. The weight of the mass is dependent onthe type and weight of the object to be transported. It may also bechosen to be above a certain mass so that it stays essentiallyunaffected by motions of the sea.

According to one embodiment, the structure comprises beams or davitsextending from the structure, wherein the first end of the guide deviceis configured to be arranged to the beams or davits.

When using beam or davits extending from the structure it is possible tolift the objects at a further distance from the structure, thus furtherminimizing the risk of collision between the structure and object to belifted during the vertical transportation.

According to one embodiment a traverse system is arranged on saidstructure configured to transport the object in a direction essentiallyperpendicular to the first direction when the object is in the elevatedposition.

When the objects has been lifted to the elevated position by the liftingdevice the traverse system may be used to transport the object to aplace in the structure more protected from the weather and the openocean.

According to one embodiment, the lifting device is a crane or a winch,arranged on the structure or configured to be arranged on or connectedwith the object.

According to one embodiment, the object is a container, equipment,person transporting arrangement, ship or vessel.

According to one embodiment, the structure is an ocean based platform.or another vessel or ship.

According to one embodiment, the weight is configured to be moveablefrom its position below the sea level to an elevated position above sealevel.

In one embodiment the weight is also moveable in a direction essentiallyperpendicular to the first vertical lifting direction, when the weightis in the elevated position. When the weight is moveable it is possibleto store both the object and/or the weight when no transportation to orfrom the structure is needed.

BRIEF DESCRIPTION OF DRAWINGS

The invention is now described, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1a shows a side view of a system according to a first embodiment ofthe invention, wherein a first type object, a boat, is arranged at sealevel position and a second type object, a container, equipment orperson transporting arrangement is transported in a first verticaldirection from the first type object to an elevated position of thestructure.

FIG. 1b shows another side view of a system according to FIG. 1 a.

FIG. 2a shows a side view of a system according to another embodiment ofthe invention, wherein a first type object, a boat, is arranged at sealevel position and the first type object is transported from sea levelposition to an elevated position of the structure.

FIG. 2b shows another side view of a system according to FIG. 2 a.

FIG. 3a shows a side view of a system according to another embodiment ofthe invention, wherein a first type object, a boat, and a weight istransported in a first vertical direction from a sea level position toan elevated position.

FIG. 3b shows another side view of the system according to FIG. 3a ,wherein the first type object and the weight is transported in a seconddirection, perpendicular to the first direction.

FIG. 3c shows a bird view of the system according to FIGS. 3a and 3 b.

FIG. 4 shows an attachment device comprising a first and secondattachment device parts attached to an object.

FIG. 5a-5c shows an attachment device in different positions.

DESCRIPTION OF EMBODIMENTS

In the following, a detailed description of the invention will be given.In the drawing figures, like reference numerals designate identical orcorresponding elements throughout the several figures. It will beappreciated that these figures are for illustration only and are not inany way restricting the scope of the invention.

FIG. 1a shows a side view of a system 1 according to the invention,wherein an object 2 in the form of a boat 2 b, transporting anotherobject 2 in the form of a container, equipment or person transportingarrangement 2 a, is arranged in a first position in relation to thesystem 1. In the first position, the stem of the boat 2 b is pointingtowards a structure 3. It is of course also possible, but not shown, todirect the stern towards the structure 3. FIG. 1b shows the FIG. 1a fromanother side, i.e. showing a rear view of the objects 2 a, 2 b. Thestructure 3 is in this embodiment an ocean based offshore platform.According to another embodiment, the structure 3 is another vessel orship essentially larger than the transport boat 2 b.

FIGS. 1a and 1b further shows a system 1 for transporting objects, suchas e.g. container, equipment or person transporting arrangement 2 a orboats or vessels 2 b from a sea level position A1 to an elevatedposition B on a structure 3 wherein the sea level position A1 is movablein relation to the elevated position B. The relative movement of the sealevel position A1 and the elevated position B is due to the movement ofthe sea itself, i.e. due to waves, currents or similar, in relation tothe rigid structure 3. A sea level position A1 is a position which isaffected by the movement of the sea, thus, the position may be at theactual sea level A0 if the object is a boat, or alternatively both aboveand below the sea level if the object is a container or equipment.

According to one embodiment, the system 1 comprises a guide device 4configured for guiding an object 2 a, 2 b from the sea level position A1to the elevated position B along a first direction parallel to theextension direction of the guide device 4, i.e. between the sea levelposition A1 and the elevated position B. The guide device 4 isconfigured to be arranged to the structure 3 in one end and to extendbelow the sea level A0 with a second end. According to one embodiment,the first direction is a vertical direction y. According to oneembodiment, shown in FIG. 1 b, the guide device 4 comprises two parallelarranged guide wires 4 a, 4 b having a distance from each other. Theguide wires 4 a, 4 b may be made of steel. According to one embodiment,the wires have a diameter of 60-90 mm preferable 70-80 mm, mostpreferably 76 mm. According to one embodiment, the guide device 4 is20-50 m long. According to one embodiment, the guide device 4 is 30-40 mlong. According to one embodiment, the distance between the guide wires4 a, 4 b may be kept constant by a beam 4 c extending between the guidewires 4 a, 4 b. Alternatively, the distance between the guide wires 4 a,4 b is adjustable by means of distance adjusting device which maycomprise a telescopic beam or other length adjustable solution. The beammay be a metal beam. The distance between the guide wires may bedetermined by the size of the object to be transported.

According to one embodiment, the guide device 4 is attached to thestructure 3 at a fixation point. This point is located above sea levelA0, preferably above the elevated position B. The structure may comprisebeams or davits 3 a extending from the structure 3, wherein the firstend of the guide device 4 is configured to be arranged to the beams ordavits. The end of the guide device 4 may not be the actual end of theguide wires 4 a, 4 b or other embodiments of the guide device 4,however, the fixation point of the guide device 4 in the structure 3defines the end of the guide device 4. In one preferred embodiment, theguide device is pivotably or rotatably attached to the structure in thefixation point. I.e. the attachment allow some relative movement betweenthe guide device 4 and structure 3.

The system 1 further comprises an attachment device 5 configured to bearranged on the object 2 a, 2 b and for attaching the object 2 a, 2 b tothe guide device 4. The attachment device 5 is configured to allow arelative movement of the attachment device 5 and the guide device 4along the first direction between the sea level position and theelevated position, and to restrict movement along a directionperpendicular to the first direction but still allowing a small playbetween the attachment device and guide device. According to oneembodiment, the attachment device 5 is fixedly arranged on the object 2a, 2 b. According to one embodiment the attachment device 5 comprises afirst and second attachment device part 5′, 5″ arranged to grip therespective guide wire 4 a, 4 b. The attachment device 5 is furtherdescribed in FIG. 4a -4 c.

The system further comprises a lifting device 8 configured to lift theobject 2 a, 2 b along the guide device 4 the first direction between thesea level position and the elevated position. According to oneembodiment, the lifting device 6 is a crane or a winch (not shown),arranged on the structure 3. According to one embodiment, the liftingdevice 8 is arranged on the object 2 a, 2 b itself and configured tointeract with the structure 3 such that a relative movement between theobject 2 a, 2 b and the structure 3 can be generated. For example, awinch or similar may be arranged on the object 2 a, 2 b wherein a wire 8a extending from the winch may be arranged in or guided via a positionin the structure 3, which is located at a point near the elevatedposition. The fastening point for the wire may thus be on the object 2a, 2 b itself if there is a guiding point in the structure 3. Uponactivating the winch, the object is pulled from the sea level positiontowards the elevated position. When the object 2 a, 2 b reaches theelevated position B it can be attached to fixed straps or other objects.This will enable the lifting device 8 to be released and used to moveother items.

The system further comprises a weight 6 which is arranged to the secondend of the guide device 4 below the sea level for stabilizing the guidedevice 4. Hence, the second end of the guide device 4 is a free end andthe weight 6 is a free weight, in that the weight 6 itself is connectedonly to the second end of the guide device 4 and that the second end ofthe guide device 4 is connected only to the weight 6. Thus, the free endand free weight is slightly moveable with the structure and oceancurrents in all directions in space. However, the weight is chosen tohave a mass so heavy that the free weight and free end is keptessentially stationary in the water. According to one embodiment, theweight 6 has a mass of 3-10 tons, preferably 5-7 tons, most preferably 6tons. However, other masses are also possible since the weight is alsodependent on the type and weight of the object to be transported.According to one embodiment, there is no further connection points tothe guide device 4 between the first end and the second end of the guidedevice 4. As a result, the guide device 4, especially when in the formof two guide wires 4 a, 4 b, are kept stretched by the weight 6 attachedat their second ends. According to one embodiment, the length of theguide device 4 is such that the weight is arranged to the second end ofthe guide device 4 at a position at least 5 m below sea level,preferably at least 10 m below sea level, whereby the guide device 4 isunaffected by motions of the sea. According to one embodiment, theweight 6 comprises two separate blocks 6 a, 6 b connected by a beam,e.g. a steel beam. The respective block may then be connected to arespective guide wire 4 a, 4 b. The beam further aids to keep the guidewires 4 a, 4 b at a constant distance from each other. According toanother embodiment the weight 6 is made in one piece as a single unitand extend between the guide wires 4 a, 4 b to keep the distance betweenthe guide wires constant.

According to one embodiment, both the object 2 a, i.e. the container orequipment to be transported as well as the boat 2 b may be attached tothe guide device 4. I.e. one attachment device 5 may be arranged on eachobject in order to guide both objects when lifted or to moveably attachthe second type object 2 b, a boat, to the structure when a second typeobject 2 a, a container or similar, is guided by the guide devicetowards the elevated position. If more than one object is to be attachedto the guide device at the same time, for example a boat and a containerwhere only the container is to be lifted, it is preferred that therespective attachment device are arranged at the respective object sothat it is possible to attach the objects on different horizontallevels.

FIG. 2a shows a side view of a system according to the invention andFIG. 2b shows a rear view of the system, wherein the object 2 is a boator vessel 2 b. The boat or vessel 2 b is disclosed in a first positionat sea level A1 an when lifted a certain distance along the guide device4 in a first, vertical direction from the sea level position A1 towardsthe elevated second position B of the structure 3. The sea levelposition A1 is in this embodiment the actual sea level A0 since theobject is a boat. The boat is arranged in relation to the system 1 sothat a side of the boat 2 b is arranged facing the guide device 4. Theboat 2 b is flexible attached, in vertical direction, to the guide wires4 a, 4 b of the guide device 4 by help of the attachment device 5 whichis fixed to the boat 2 b. The attachment device 5 comprises a first andsecond attachment device part 5 a, 5 b arranged to grip the respectiveguide wire 4 a, 4 b. In order for the boat 3 b to have a freetransportation way, the guide wires 4 a, 4 b are attached in one end tobeams or davits 3 a extending from the structure 3. The guide wires 4 a,4 b are in their other end attached to the weight 6. The connection ofthe boat 2 b to the guide wires 4 a, 4 b enables hoisting of the boatwithout the boat rotating and swinging. By help of a lifting device 8placed on a platform on the structure 3 and a wire 8 a extending fromthe lifting device 8 to the boat 2 b, the boat is transported from thesea level to the elevated position. When the boat is in the elevatedposition, persons or equipment may safely be embarked from the boat tothe structure without risking injury. When in its elevated position itis also possible to release the boat 2 b from the lifting device andsecure it to the structure with other means, for example davits. It isthe possible to use the lifting device 8 for other purposes.

FIGS. 3a, 3b and 3c shows another embodiment of the system according tothe invention. In this embodiment the weight 6 is configured to bevertically moveable from its position below the sea level to an elevatedposition B2 above sea level in a first direction y. The elevatedposition B2 is in this embodiment essentially the elevated position B,but any other elevated position is possible. At least one winch 9 orother type of lifting device is arranged to move said weight 6 byhoisting the guide wires 4 a, 4 b. In one embodiment the weight islifted a time period after the object is lifted. In some conditions itis also possible to lift the weight simultaneously with the object.

In one embodiment a traverse system 11 is arranged on the structure 3.The traverse system 11 may comprise one or more horizontally arrangedbeams 11 a extending from the structure 3. The traverse system 11 isconfigured to transport the object, i.e the boat and/or equipment 2 a, 2b in a direction x essentially perpendicular to the first verticallifting direction y when the object 2 a, 2 b is in the elevated positionB. I.e. when the boat and/or equipment has been lifted to the elevatedposition by the lifting device 8 it can be transported to a place in thestructure 3 more protected from the weather and open ocean. In oneembodiment the weight 6 is also moveable in a direction x essentiallyperpendicular to the first vertical lifting direction y, when the weightis in the elevated position B2. The object 2 a, 2 b and/or the weight 6is thus safely stored when no transportation to or from the structure 3is needed. The wires 4 a, 4 b attached to the weight 6 and the wire 8 aattached to the object to be lifted 2 a, 2 b may run in a system ofblocks and tackles 11 b to optimize the lifting capacity of the systemand to enable the horizontal movement. Both the guide device 4 and thelifting wire 8 a may, in one embodiment, be attached to a singlestructure 11 a moveable in the horizontal direction. Thus, when both theboat 2 b and the weight 6 is in the elevated position B2, the singlestructure 11 c is moved horizontally. In one embodiment, the singlestructure 11 a is fixed in relation to the transverse system 11 and theentire transverse system 11 comprising beams is moved horizontally inthe x-direction by a movement device of any kind.

FIG. 4 disclose an embodiment of the attachment device 5. The attachmentdevice 5 comprises a first and second attachment device part 5′, 5″arranged to grip the respective guide wires 4 a, 4 b of the guide device4. The respective attachment device part 5′, 5″ are attached to theobject 2 a, 2 b with a distance adapted to the distance between theguide wires 4 a, 4 b. When the object 2 a, 2 b is docked to the guidedevice 4, the respective attachment device part 5′, 5″ catches the guidedevice and partly grip the respective wire 4 a, 4 b.

According to one embodiment, shown in FIGS. 5a -5 c, the attachmentdevice 5 comprises a hook or openable ring 5 b arranged in a housing 5a. The hook 5 b is rotatable around a first end by a rotation device 5 cfor releasable attaching the attachment device 5 around the guide device4 in the form of e.g. guide wires 4 a, 4 b.

FIG. 5a-c shows the hook 5 b in a first, second and third position. Inthe first position, FIG. 5a , the hook is stored away. In the secondposition, FIG. 5b , the hook is rotated so that it easily catches theguide device and partly grip the respective wire 4 a, 4 b. In the thirdposition, FIG. 5c , the hook is in its locked position where a relativemovement in a first direction, i.e. a vertical lifting direction, isallowed and a movement perpendicular to the first direction isrestricted. Within the meaning of a restricted movement, a certainlimited movement may be allowed due to variations or slight differencesbetween the guide wire diameter and the diameter of the hook or openablering. A restricted movement may also be an entirely restricted movement,i.e. wherein no relative movement is allowed and the hook or openablering is locked in relation to the guide wires 4.

A preferred embodiment of a system for transporting objects from a sealevel position to an elevated position according to the invention hasbeen described. However, the person skilled in the art realizes thatthis can be varied within the scope of the appended claims withoutdeparting from the inventive idea. It is of course also possible to usethe same system for transporting objects from an elevated position to asea level position.

All the described alternative embodiments above or parts of anembodiment can be freely combined without departing from the inventiveidea as long as the combination is not contradictory.

1. A system for transporting from a sea level position to an elevatedposition on a structure, wherein the sea level position is movable inrelation to the elevated position, wherein the system comprises; anelongated guide device configured to be arranged to the structure in oneend and to extend below the sea level with a second end, an attachmentdevice configured to be fixedly arranged on said object and forattaching said object to the elongated guide device, wherein theattachment device is configured to allow a relative movement between theattachment device and the elongated guide device along a first directionparallel to the extension direction of the guide device, and to restrictmovement along a direction perpendicular to the first direction, alifting device configured to transport the object from the sea levelposition to the elevated position, wherein a weight (is arranged to thesecond end of the guide device below the sea level for stabilizing theguide device, wherein the second end is a free end and the weight is afree weight.
 2. The system according to claim 1, wherein the attachmentdevice is configured for guiding the object from the sea level positionto the elevated position along the elongated guide device whentransported by the lifting device.
 3. The system according to claim 1,wherein the weight is arranged to the second end of the guide device ata position at least 5 m below sea level, preferably at least 10 m belowsea level, whereby the guide device is unaffected by motions of the sea.4. The system according to claim 1, wherein the guide device comprisestwo parallel arranged guide wires having a distance (d) from each other.5. The system according to claim 4, wherein the distance (d) between theguide wires is kept constant by a beam extending between the guide wiresor wherein the weight is made in one piece and extend between the guidewires.
 6. The system according to claim 4, wherein the guide wires aremade of steel.
 7. The system according to claim 4, wherein theattachment device comprises a first and a second attachment device partarranged to grip the respective guide wires.
 8. The system according toclaim 1, wherein the weight comprises two separate blocks connected by abeam.
 9. The system according to claim 1, wherein the weight has a massof 3-10 tons.
 10. The system according to claim 1, wherein the weight isconfigured to be moveable from its position below the sea level to anelevated position above sea level.
 11. The system according to claim 1,wherein the structure comprises beams or davits extending from thestructure, wherein the first end of the guide device is configured to bearranged to the beams or davits.
 12. The system according to claim 1,wherein a traverse system is arranged on said structure configured totransport the object and/or the weight in a direction (x) essentiallyperpendicular to the first direction (y) when the object is in theelevated position.
 13. The system according to claim 1, wherein thelifting device is a crane or a winch, arranged on the structure orconfigured to be arranged on or connected with the object.
 14. Thesystem according to claim 1, wherein the object is a container,equipment or person transporting arrangement or a ship or vessel.